Jan, I went back to creating a machdep->machspec->user_eframe_offset value to be able to account for both the 4.7 and the upcoming 4.14 pt_regs changes: https://github.com/crash-utility/crash/commit/c975008e61121ef8785622c3bc26964da8fe0deb Again, though, note that "bt" does not work with 4.14. Thanks for the heads up, Dave ----- Original Message ----- > > > ----- Original Message ----- > > > > ----- Original Message ----- > > > Ok. I have seen this change in the pt_regs struct before but did not > > > connect > > > it to this problem. I see these new field in pt_regs in earlier kernel > > > versions than 4.7, but it is probably backports. It really does not > > > matter > > > for the solution of the problem. The following change works for me: > > > Change: > > > #define USER_EFRAME_OFFSET (304) > > > to: > > > #define USER_EFRAME_OFFSET (STRUCT_SIZE("pt_regs") + 16) > > > > > > Then you might want to avoid the recalculation of the struct size. I > > > think > > > your patch does the same thing. > > > > Yeah, but doing it your way makes better sense. In fact, I see that > > there's > > another commit coming down the pike in 4.14-rc1 that changes the size yet > > again: > > > > diff --git a/arch/arm64/include/asm/ptrace.h > > b/arch/arm64/include/asm/ptrace.h > > index 11403fd..ee72aa9 100644 > > --- a/arch/arm64/include/asm/ptrace.h > > +++ b/arch/arm64/include/asm/ptrace.h > > @@ -119,6 +119,7 @@ struct pt_regs { > > u64 syscallno; > > u64 orig_addr_limit; > > u64 unused; // maintain 16 byte alignment > > + u64 stackframe[2]; > > }; > > > > Thanks, > > Dave > > As it turns out, neither patch works for 4.14 with the kernel commit above. > The stackframe[2] addition essentially accounts for the 16 bytes at the > top of the stack. > > The pt_regs structure in 4.14 is 320 bytes: > > crash> pt_regs > struct pt_regs { > union { > struct user_pt_regs user_regs; > struct { > u64 regs[31]; > u64 sp; > u64 pc; > u64 pstate; > }; > }; > u64 orig_x0; > s32 syscallno; > u32 unused2; > u64 orig_addr_limit; > u64 unused; > u64 stackframe[2]; > } > SIZE: 320 > crash> > > So for example, taking a user-space task with a stacktop address of > ffff00000807c000: > > crash> eval ffff00000807c000 - 320 > hexadecimal: ffff00000807bec0 > decimal: 18446462598867566272 (-281474841985344) > octal: 1777770000001001737300 > binary: > 1111111111111111000000000000000000001000000001111011111011000000 > crash> > > Here is the pt_regs: > > crash> pt_regs ffff00000807bec0 -x > struct pt_regs { > { > user_regs = { > regs = {0x4, 0xffffe4ef4db0, 0x25, 0xffffffffffffffff, 0x0, 0x8, > 0xffffffbb, 0x0, 0x16, 0x74, 0x65, 0x67, 0x10, 0x0, > 0x1bb58f1f76129a, 0xce, 0xaaaaab21c660, 0xffffab4d35a8, > 0xaaaaab1a0aa8, 0x4, 0x0, 0xffffe4ef4db0, 0x0, 0x1, 0xaaaaab180778, > 0xaaaaab21c000, 0xaaaaab1803f0, 0xaaaaab21c000, 0xffffe4ef52b8, > 0xffffe4ef4d70, 0xffffab4d3830}, > sp = 0xffffe4ef4d70, > pc = 0xffffab4d385c, > pstate = 0x80000000 > }, > { > regs = {0x4, 0xffffe4ef4db0, 0x25, 0xffffffffffffffff, 0x0, 0x8, > 0xffffffbb, 0x0, 0x16, 0x74, 0x65, 0x67, 0x10, 0x0, > 0x1bb58f1f76129a, 0xce, 0xaaaaab21c660, 0xffffab4d35a8, > 0xaaaaab1a0aa8, 0x4, 0x0, 0xffffe4ef4db0, 0x0, 0x1, 0xaaaaab180778, > 0xaaaaab21c000, 0xaaaaab1803f0, 0xaaaaab21c000, 0xffffe4ef52b8, > 0xffffe4ef4d70, 0xffffab4d3830}, > sp = 0xffffe4ef4d70, > pc = 0xffffab4d385c, > pstate = 0x80000000 > } > }, > orig_x0 = 0x4, > syscallno = 0x16, > unused2 = 0x0, > orig_addr_limit = 0x0, > unused = 0x0, > stackframe = {0x0, 0x0} > } > crash> > > So for backwards compatibility, it will be necessary to look for the > new stackframe[2] field. > > Unfortunately there have been some other significant changes to the > unwind code in 4.14, and because of them, "bt" fails completely. > > Dave -- Crash-utility mailing list Crash-utility@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/crash-utility
